show Abstracthide AbstractPhosphate is a necessary macronutrient for basic biological processes, plant growth, and agriculture. Plants modulate their root system architecture and cellular processes to adapt to phosphate deprivation albeit with a growth penalty. Excess application of phosphate in the form of fertilizer can lead to eutrophication and has negative environmental impact. Moreover, phosphate mined from rock reserves is a finite and non-recyclable resource and its levels are nearing complete depletion. Here, we show that Solanum pennellii, a wild relative of tomato, is partially insensitive to phosphate deprivation. Furthermore, it mounts a constitutive response under phosphate sufficiency. We demonstrate that activated brassinosteroid signaling through a tomato BZR1 ortholog gives rise to the same constitutive phosphate deficiency response which is dependent on over-accumulation of zinc. Collectively, these results reveal an additional strategy by which plants can adapt to phosphate starvation. Overall design: 35S:TRAP construct-containing tomato seedlings were harvested between eight and ten days after germination. Two tissues were extracted for analysis, the root tip and the root midsection. A total of 4 biological replicates for each genotype and treatment were used with between 30 and 40 plants in each biological replicate.